Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine vane and blade assemblies and turbine rotors to these high temperatures. As a result, turbine rotors must be made of materials capable of withstanding such high temperatures. Steel rotors have begun to be changed to nickel-based alloys to compensate for these high temperatures. However, rotors are large components and forming the rotors entirely of nickel-based alloys is expensive. Thus, a need exists for a more cost efficient turbine rotor having superior thermal properties.